Steering mechanism for ships

ABSTRACT

Fluid actuators for rotating a rudder stock of a ship utilizing a plurality of cylinders with piston rods or rams that operate a tiller attached to the rudder stock. Provision is made for selfalignment of the actuator and the tiller.

United States Patent William E. Heese Akron, Ohio June 6, 1968 July 27, 1971 1 Allen Electric and Equipment Company inventor Appl. No. Filed Patented Assignee STEERING MECHANISM FOR SHIPS 11 Claims, l3 Drawing Figs.

U.S. Cl "114/150 B63h 25/30 FieldoiSenr-eh 114/150; 60/52 S. 92/166 References Cited UNITED STATES PATENTS 3,335,642 8/1967 Rosaenn t. 92/165 X Primary Examiner-Andrew H. Farrell Attorney-Watts, Hoffman, Fisher and Heinke ABSTRACT: Fluid actuators for rotating a rudder stock of a ship utilizing a plurality of cylinders with piston rods or rams that operate a tiller attached to the rudder stock. Provision is made for self-alignment of the actuator and the tiller.

PATENTED JULZ"! 1911 359519? SHEET 1 UP 4 F 2 INVENTOR.

WILLIAM E. H5555 ATTORNEYS.

INVENTOR. WILLIAM E. H5555 BY 9mm, G b M M ATTORNEYS SHEET 3 OF 4 m QNN m PATENTED JUL27 I97! sm o 0 m now I o sw mQN It! a v Q STEERING MECHANISM FOR SHIPS This invention relates to ship steering mechanisms and more particularly to asteering mechanism including a novel rotary fluid actuator.

Large ships require actuators capable of exerting high torque to turn the rudder of theship. Such actuators must be capable of operating against the large forces exerted by the water against the rudder blade when the ship is moving.

Typically, four hydraulic cylinder and piston actuators are secured directly to the hull of the ship, for example, to rigid frame or'base members. A tiller connected rudder stock is rotated-by the actuators to move the rudder. A particularly troublesome problem has been aligning the hydraulic cylinders and associated piston rods with respect to the rotational axis of the rudder stock so that the mechanism functions smoothly and properly; Where four cylinders are used, each must be accurately aligned individually. Alignment is difficult with the large and heavy cylinders that are required. The mounting and alignment mechanisms must withstand the large forces and weight of components and yet must provide a high degree of accuracy. Normal flexing of the ship structure can cause distortion of such mechanisms, which destroys the alignment. Moreover, greater stresses, as experienced during collision, explosion or other occurrence which inflicts damage on the ship can readily cause severe distortions that may well result in a jammed rudder.

In the past, alignment of the actuating cylinders with the shaft or rudder stock has been accomplished by providing a the large loads and bending momentsinvolved. Additional plurality of shims between split portions of each cylinder and support base. Fine alignment adjustments must be made during assemblyand again during installation. Due to the large number of shims and the weight and size of the components, this procedure is time consuming and results in considerable installation effort and expense. These and other disadvantages of known arrangements have been overcome by steering mechanisms embodying the present invention.

One embodiment of this invention comprises a rotary member or tiller and a stationary actuator that couple directly toand are supported on the top of a rudder stock. Rams or piston rods associated with multiple cylinders of the actuator are connected to the rotary member. The rams or piston rods are moved transversely of the rudder stock by the alternate introduction and withdrawal of fluid under pressure to the cylinders. This in turn rotates the rotary member and connected rudder stock. Rotation of the actuator from the reaction torque is prevented by brackets or abutments that are secured to the ship and which absorb torque and dampen shock. Because the rotary member and stationary actuator are directly supported as a single unit upon the top of the rudder stock, no alignment is necessary with an additional fixed reference. Thus, no shims or other adjusting mechanisms are needed, and installation procedures are greatly simplified.

This arrangement has the great advantage of providing an actuator that floats with the stock, so that it moves in response to deflection of the rudder stock. This isolates the actuator from distorting forces ship flexure.

ln another embodiment of this invention the actuator cylinder and rams are supported by housings mounted directly to the ship hull but provide a connection between the rams or piston rods and the tiller that permits limited universal movement therebetween, eliminating the need for accurate, critical, alignment of the cylinders and housings.

In addition to the novel arrangements of the steering mechanisms, improved constructions of the actuators themselves have been provided. The large forces and large size of the actuator required to rotate a rudder stock create many problems not encountered with smaller actuators. These problems include (1) balancing the large torques that are required, (2) overcoming the separation forces between the rotary element and the actuating'piston rods or rams when torque of high magnitude is applied, (3) compensating for slight operating misalignments among pistons, cylinders and rotary members, which are unavoidable in components of the size involved, (4) piston and cylinder wear caused by the (5) allowing for deflection of the shaft'or rudder stock due to problems exist in maintaining and servicing actuators without shutting down operations. It is especially important that steering mechanisms for ships remain continually operable.

With the present invention, rotary fluid actuators are provided that overcome the above mentioned problems, and which are also versatile, relatively simple and rugged in construction, and reliable in performance under extremely heavy load conditions.

Balanced torque is provided by an arrangement of cylinders and pistons that are located on diametrically opposite sides of the shaft to be rotated. The cylinders extend transversely of the shaft. Eight cylinders are provided in the preferred-construction. They are arranged in opposed pairs with the cylinders of each pair extending from opposite sides of a central housing that surrounds an end of the shaft to be rotated. Two such pairs are located on one side of the shaft and two on an opposite side. A piston or ram slides within each cylinder. Where a ram is used opposite ends'of the ram slide in onev of two opposed cylinders and the end surfaces of the ram act as pistons. Where pistons are used a piston rod connects the pistons of two opposed cylinders. The ram or piston rod extends between the cylinders and either through a central housing or'between two spaced housings. Thus, four piston rods extend across the shaft, two on each side. A rotary member or tiller is located within the central housing, coupled to the surrounding a portion of the shaft. Each of the four piston rods is in turn coupled to the rotary member. When the piston rods on opposite sides of the shaft are driven in opposite directions they act as a couple and apply a balanced torque to the rotary member and shaft.

Large forces are needed to rotate the shaft to which the actuator is connected. Components of these forces create a side thrust and act to separate the piston rods or rams from their location adjacent the shaft. In one embodiment of this invention such separation is opposed by bearing pads or shoes that are mounted in the central housing along the path of reciprocation of each piston rod. The bearings are positioned at locations of maximum side thrust along each piston rod to resist the side load on the rods and prevent bowing of the rods and separation from the shaft. Such bowing andseparation not only causes wear, but also causes inaccuracy in the degree of rotation of the shaft. In another embodiment such separation is resisted by utilizing a ram of large cross sectional area and by locating the sealing and bearing surfaces between the cylinders and ram at inner ends of the cylinders, close to the central area of the actuator, rather than at the opposite ends of the rams, to minimize the span between support points of the ram.

Where opposed bearing pads or shoes are used to oppose separation of piston rods from their intended location, operating misalignments that may occur between piston rods and the bearing pads or shoes are compensated for by the bearing construction. Radiused back walls of the bearings fit into radiused seats in the housing. The bearings are held in place by a connection that allows limited rotation in the grooves.

Similarly, pistons secured at each end of the piston rods are designed for floating action relative to the rods. The pistons consists essentially of discs attached to the ends of the piston rods by means of a lost motion device, such as a central cap screw inserted through an oversized hole. Only the floating heads contact the cylinder walls. This allows the piston heads to move as required minimizing the transmission of side lead forces from the piston rods. As a result, wear of the packing rings and cylinder walls is minimized, notwithstanding the high leverage possible and magnitude of forces involved. Moreover, the heads are readily movable, to simplify the packing procedures. This can be accomplished from the ends of the cylinders and can be done while the actuator is operated by other cylinders.

A further problem involved with actuators for use in steering mechanisms or with other large equipment is the difficulty of obtaining parts of the large sizes necessary. Actuators as contemplated herein are on the order of 6 to 12 feet in total length and may weigh from 3 thousand to 30 thousand pounds or more. The rudder stock may be I to 3 feet in diameter. Ifa spur gear is to be used as the rotary member connected with the rudder stock or other large shaft, to be driven by racks moved by pistons, the gear may need a face width as great as 3 feet. The problems and expenses in obtaining such a gear are manifest. To overcome this difficulty, a linkage is provided that is especially well adapted for use with four piston rods arranged in pairs on each of two diametrically opposite sides of the shaft to be rotated. A tiller is fixed to the shaft to be rotated and has two diametrically opposite portions that extend beyond the shaft and between the two piston rods or rams on each opposite side of the shaft. A radial slot is provided in the tiller in each extending portion. A connecting pin extends between the two piston rods on each side and is received in a radial slot of the tiller. Reciprocation of the pistons and rods moves the slider pin transversely of the shaft. This rotates the rotary member and shaft. The radial slots are of sufficient length to accommodate necessary sliding movement of the pins in the slots. Such an arrangement is considerably less expensive than a rack and pinion interconnection. A pin construction is provided that minimizes wear, and the arrangement is such that replacement of worn parts can be conveniently accomplished without complete disassembly. In addition, the rotary member need not be of a width sufficient to directly interconnect the two piston rods on each side of the shaft, which are spaced axially along the rotated shaft. Instead, the rotary member is relatively thin and lies between the spaced piston rods. Where the actuator is directly secured to the ship hull, a self-aligning bearing is interposed between the piston rods or rams and the radial slot of the tiller to compensate for misalignment between the connecting pin and tiller in the event the cylinders are not perfectly aligned relative to each other or relative to the rudder stock, and to assure even load distribution.

An important feature of the present actuators is that while the cylinders on opposite sides of the rudder stock function as a couple in the typical operation, each half of the couple can function independently. Thus one half can be removed and repaired or replaced without shutting down operations or in some instances only one half of the actuator need be installed initially. In the embodiment that is carried on the end of the rudder stock, this separable feature is attained by providing a housing that is split vertically so that each half includes two opposed pairs of cylinders on one side of the shaft. In the embodiments that are secured directly to the ship hull, separate housings are provided on opposite sides of the rudder stock so that removal of the cylinders on one side does not structurally affect the cylinders and operating linkage on the other side.

Accordingly, the objects of this invention are to provide novel steering mechanisms and improved actuators for rotating rudder stock or the like, and which are capable of exerting high torque.

These and other objects, features, and advantages of this invention will become better understood by reference to the following detailed description, when considered in connection with the accompanying drawings, in which:

FIG. I is a top plan view of one embodiment of an actuator of the present invention, shown mounted on top of the rudder stock ofa ship;

FIG. 2 is a side elevational view of the actuator of FIG. 1, showing the manner in which it is mounted on top of the rudder stock;

FIG. 3 is a plan view ofthe actuator as shown in FIG. 1, with parts broken away and with parts in section, illustrating the construction ofthe actuator and the manner in which it is connected to the shaft to be rotated;

Fig. 4 is an end elevational view, partly in section, of the actuator shown in FIG. 3, showing details of the construction of the actuator housing and connection between the actuator and the shaft to be rotated;

FIG. 5 is an enlarged portion of FIG. 4 showing constructional details;

FIG. 6 is a plan view of another actuator embodying the present invention, shown supported on a ship hull and connected to a rudder stock;

FIG. 7 is a side elevational view of the actuator of FIG. 6;

FIG. 8 is an end view partly in elevation and partly in section of the actuator of FIG. 6, taken along the line 8-8 of FIG.

FIG. 9 is a detailed sectional view of the coupling assembly interconnecting the actuator and a tiller on the rudder stock, taken along the line 9-9 of FIG. 6;

FIG. 10 is a partial detailed view of the coupling assembly of FIG. 9 on an enlarged scale, taken along the line 10-10 of FIG. 6; Y

FIG. 11 is a fragmentary sectional view on an enlarged scale showing constructional details of the mounting arrangement of the cylinders of FIG. 6;

FIG. 12 is a plan view of two actuators each comprised of half of an actuator of the general type shown in FIG. 6 connected to separate rudder stocks and linked together for coordinated movement; and

FIG. 13 is a fragmentary plan of an actuator similar to the actuator shown in FIG. 6 but with a modified cylinder construction.

Referring now to the drawings, one embodiment of a steering mechanism for a ship is shown in Figures 1 and 2. A fluid actuator 10 is mounted on the upper end ofa vertical, rotatable shaft 12, forming the rudder stock of a ship. The shaft is connected to the rudder of the ship (not shown) in a conventional manner. As diagrammatically shown, the rudder stock 12 is journaled for rotation about a vertical axis in a journal housing 14 and extends above a deck 15. The upper end ofthe shaft forming the rudder stock extends above the journal housing 14. The actuator 10 is secured against rotation by brackets 16 secured to the deck 15 and which function as abutments in contact with the actuator.

As shown in Figures 1 to 3, the basic components of the actuator 10 include a split central housing 20, a plurality of opposed cylinders 22 extending from the housings 20, pistons 23 within the cylinders 22, piston rods 24 extending through the housing 20, a rotary member 26 within the housing 20 and a coupling assemble 28 interconnecting the piston rods 24 and the rotary member 26. The mechanism shown is an extremely large assembly and the particular construction and arrangement facilitates the large size and forces involved. By way of illustration, the vertical shaft 12 represents a 12 inch diameter rudder stock of a large ship. The actuator 10 required for rotating this shaft is approximately 2 feet high, 6 feet long and weighs over a ton and a half. A torque of between 3 and 4 million inch-pounds can be exerted by the actuator in rotating the shaft. This is attained by introducing hydraulic fluid under pressure to the cylinders, often under pressures as great as 2,500 to 3,000 pounds per square inch. Other actuators of this construction are capable of exerting torques of 40 to 50 million inch-pounds.

As best seen in FIGS. 1,2 and 3, a preferred embodiment of the actuator utilizes 8 separate cylinders 22a, b, c, d, e,f, g, It. Cylinder 22f is not shown, but is positioned beside cylinder 22b and beneath cylinder 22h. The cylinders are arranged in opposed aligned pairs 22a, b; 22c,d; 22e,f; and 223, h. The cylinders of each pair are on opposite sides of the housing 20. Two pairs 22a, b and 220, d are positioned on one side of the shaft 12 transversely of the axis and tangential to the shaft. The other two pairs 22e,fand 22g, h are similarly located on an opposite side of the shaft, diametrically across from the first pairs. Opposed cylinders 22c, d are directly above cylinders 22b and spaced therefrom axially of the shaft 12. Similarly, cylinders 223, h are directly above and spaced from cylinders 22e,f.

Inner ends of the cylinders 22 are connected to the housing 20. The housing 20 is a boxlike affair having two spaced, vertically split, end walls 32, 34 and two spaced sidewalls 36, 37. See FIG. 3. The housing 20 and rotary member 26 will be described in more detail subsequently. For immediate purposes it is sufficient to note that the walls 32, 34 each have four spaced circular openings 38 that receive the inner ends of the cylinders 22.

Each cylinder is constructed in the same manner, and only the detailed construction of cylinder 22c will be described. As best shown in FIG. 3, cylinder 22c is formed of a tubular wall 40, which may be formed of brass, steel or other suitable material. An open inner end 41 is formed with a reduced outside diameter and is received in the circular opening 38 of the side wall 32.'A radial face 42 formed, in the wall 40 by the reduced outside diameter of the end portion 41 abuts against the outside surface of wall 32. This locates the tubular wall 40 with respect to the wall 32.

The outer end of the tube 40 is closed by an end cap 44 made ofsteel or the like and provided with a port 46 through which fluid under pressure can be introduced to the cylinder 22c to drive the piston 23, or through which fluid can be exhausted to permit movement of the piston 23 toward the end cap. The end cap 44 fits over the end of the cylinder. A cylindrical surface 49 encircles the cylinder end and carries an O- ring 50. The end cap is rectangular is shape and extends across two vertically adjacent cylinders, as best shown in FIG. 4 extending across cylinders 22e, g. Separate cylindrical surfaces 49 receive the two adjacent cylinder ends.

Tie rods 52 extend the lengthof each cylinder. One end of each tie rod 52 is threaded into a bore in the sidewall of the housin'g 20. The opposite end extends through one ofa plurality of holes in the associated end cap 44. A nut 56 is threaded on the end of the tie rod 52 to clamp the end cap 44 against the ends of the two adjacent cylinders.

As best illustrated in FIG. 4 in connection with cylinders 222, g, fluid conduits'58 connect the ports 46 of the end caps 44 of vertically adjacent cylinders 22. The conduits are connected by an external port 59 to a main conduit (not shown). With this arrangement, fluid is either introduced or withdrawn from both the vertically adjacent cylinders 22a, 0; 22b, a; 22e, g; and 22f, h simultaneously so that vertically adjacent cylinders function in the same manner at the same time. All four external ports 59 are connected by main conduits andsuitable controlled valves to fluid under pressure and to exhaust. The arrangement is such that the cylinders 22a, c and 22f, g are connected to the same pressure at the same time, for example, to a positive pressure, while the other four cylinders are connected to exhaust.

A piston 23 is located in each cylinder 22. A total of four piston rods 24 are provided in the actuator 10. One piston rod extends between the two pistons of the opposite cylinders 22 of each pair. This is best shown in FIG. 3 in connection with the piston rod 24 associated with cylinders 22c, d. The construction and arrangement is identical for all four cylinder pairs, and only the construction in cylinders 22c, d will be described in detail.

Two circular pistons 23 are fastened to opposite ends of a common piston rod 24. Each piston head includes an annular sealing member 62.

The piston rod 24 is cylindrical expect for upper and lower flat wall portions 65, 67. See FIGS. 3 and 4. The piston rod extends across the width of the housing adjacent to and transversely of the shaft 12. The length of the piston rod 24 with respect to the cylinders 22 and housing 20 is such that each piston 23 remains within the associated cylinder during reciprocation. Thus, when the piston in cylinder 220 is in a position adjacent the cylinder end cap 44, the other piston is adjacent the inner end of cylinder 22d, adjacent the sidewall 34 of the housing 20.

The pistons 23 are secured to the piston rod 24 in a manner that permits relatively free or floating movement of the pistons relative to the rod. One suitable arrangement is to secure the pistons to the end of the rod 24 with cap screws that pass through oversized holes in the piston heads. Another suitable arrangement for providing floating connections is shown in the copending application of Paul Carr, Ser. No. 3 I 8,266 filed Oct. 23, i963 and entitled Air Actuator.

As generally described above, the piston rods 24 and associated pistons are reciprocally disposed in the cylinders 22 and central housing 20. The path of reciprocation is generally defined by the tubular walls of the cylinders 22. Each piston rod is further guided in its reciprocal path by two spaced side bearings 72, 74 adjacent end walls 32, 34, respectively. See FIGS. 3 and 4. These bearings carry the side loading on the piston rods. Their location adjacent the end walls places them at the location where the maximum side thrust is created by the angular relationship between the rotary member 26 and the piston rods 24. Each side bearing is constructed the same and only side bearing 72 will be described in detail.

The side bearing 72 has a concave cylindrical front surface 76 that bears against the outside cylindrical side surface of the associated piston rod. The bearing is radiused on a back surface 77 to fit into a radiused bearing seat 79 in the respective sidewall 36, 37 of the housing 20. The bearing is held in place by screws 80 extending through the bearing seat. it is desirable to mount the bearings for limited floating movement to compensate for slight operating misalignments of the piston rods or for flexure of the piston rod. This is provided by securing the bearings with cap screws 80 in oversized holes.

Referring now to FIGS. 3 and 4, the rotary member 26 is shown extending radially from the shaft 12, between the verti- 'cally spaced piston rods 24 on each side of the shaft. The rotary member is a tiller having a circular, tapered central aperture 82 that fits about a tapered top portion 84 of the shaft 12. A plurality of keys 86 couple the rotary member 26 to the shaft 12 so that the two rotate together. in alternative embodiments, the rotary member can be keyed to a cylindrical shaft or can be provided with a polygonal opening or the like that fits over a mating top portion of the shaft, with the member riding on a shoulder of the shaft.

The rotary member or tiller 26 is elongated in two opposite directions, with portions 26a, 26b extending between the vertically spaced piston rods 24 on each side of the shaft 12. A radial slot 90 is provided in portion 26a and a radial slot 92 is provided in portion 26b. The radial slots 90, 92 diametrically opposite each other and extend through the entire height of the rotary member 26. The radial slots each receive a coupling assembly 28 carried by the piston ro'ds on each side of the shaft 12.

Each coupling assembly 28 extends between upper and lower spaced piston rods 24 on each side of the shaft 12. The upper and lower piston rods each include a vertical through bore 95 at the center of the rod. A single connecting pin 96 extends through the bores 95 of each pair of piston rods. The pin 96 includes a head 97 and a keeper grooves 98, which extend above the flat top surface 65 of the associated upper piston rod 24. Two flat pin keeper plates 99 are secured to the top surfaces 65 of the piston rod by screws 100, on opposite sides longitudinally of the through bore 95. The plates extend into partial overlying relationship with the throughbore and into keeper grooves 98 beneath the head 97. The keeper grooves have flat inner seating surfaces 101 that extend transversely of the piston rod axis. These surfaces are engaged by flat ends of the keeper plates. Thus, the keeper plates 99 retain the pin in proper vertical position and also prevent rotation of the pin during reciprocation of the piston rods 24. This eliminates wear between the pins and the piston rods.

A bearing block 104 surrounds a central portion of each pin 96, between the spaced piston rods 24. As best illustrated in FIG. 3, the bearing blocks 104 are essentially square in plan and essentially equal in width to the width of the associated slot 90 or 92. As is shown, each slot 90, 92 is considerably deeper than the depth of the associated bearing block. The height of the bearing blocks 104, as shown in FIG. 4, is substantially the same as the thickness of the extending portions 26a, b of the rotary member 26 and tits closely between the facing surfaces of the adjacent piston rods 24. The bearing blocks 104 pivot with respect to the pins 96 during reciprocation of the piston rods 24. They also slide in the grooves 90, 92 of the rotary member 26. To assure that the bearing block rotates freely with respect to the pin 96, lubricating holes 105 are provided through the pin 96 to the inner surface of the bearing block. A screw 107 is threaded into the top of the pin 96, closing the vertical lubricating hole 105. The screw 107 can be replaced by a threaded rod to remove the pin from the piston rods and housing.

The housing 20 is split vertically through the center, so as to be formed of two halves 20a, 20b. The one half 20a includes the side wall 37, half of the two end walls 32, 34 and half of a top wall 106 and bottom wall 108. The other half 20b includes the side wall 34 and the other halves of the end walls 32, 34, top wall 106 and bottom wall 108. Each half has a peripheral flange 110a, 110b where the two halves abut each other. Flat abutting surfaces 1120, 112b and body keys 114 in the abutting faces of the flanges accurately locate the two halves in adjoining relationship encircling the shaft 12. Bolts 116 extend through the flanges 110a, 110b and secure the two halves of the housing together. With this arrangement, one halfof the housing 20a or 20b and the associated cylinders 22 and piston rods 24 can be removed from the shaft 12 and the rotary member 26 while the remaining half of the actuator can continue to function, being supported on the shaft 12 by the rotary member 26.

The top wall 106 has a circular central opening 118 and the bottom wall 108 has an aligned circular central opening 120. The shaft 12, including a top rudder stock extension 122 extends through these openings. The tapered top portion 84 of the shaft 12 and the rotary member 26 are located within the housing 20.

A lower bearing flange 124 is secured to the bottom wall 108 of the housing in the opening 120 and is secured by bolts 126. An O-ring 128 in the flange 124 provides a seal between the flange and the shaft 12. A lower bushing 130 is supported by the bearing flange 124 in circumferential contact with the shaft 12, just beneath the tapered portion 84.

In a similar manner a top bearing flange 132 in the top opening 118 is secured by bolts 134 to the top wall 106 of the housing This flange retains an upper bushing 136 about a hold down ferrule 138 that surrounds the top rudder stock extension 122. The hold down ferrule 138 rests upon the upper edges of the keys 86. A hold down plate 140 fastened by bolts 142 (FIG. 3) retains the hold down ferrule 138 against the keys 86.

An opening 144 is provided in the top surface 106 of the housing above the top piston rods 65, to provide access to each of the pins 96 for removal. A plate 145 covers each opening 144. An opening 148 is provided in each side wall 36, 37, providing access to the coupling mechanisms 28 from each side of the housing 20. When a pin 96 is removed through an associated top opening 144, the bearing block 104 can be removed through the side opening 148. This facilitates repair or replacement of worn parts without disassembly of the housing. Plates 149 cover the openings 148. The openings 148 and plates 149 provide clearance for the rotary member 26 to rotate from one extreme position as shown in FIG. 3, where it is in contact with an adjustable stop 152, through a central transverse position, to an opposite position against a stop 153. This movement of the member 26 rotates the shaft 12 through approximately 70 to 74.

It will be evident from the above described apparatus that the actuator is supported by the rudder stock 12, which is to be rotated by the actuator. The upwardly tapered portion 84 of the rudder stock supports the rotary member 26 at a fixed vertical location. The member 26 in turn supports the upper piston rods 24 which support the central housing 20 through the associated cylinders 22. The housing then supports the lower cylinders and piston rods. The only connection between the actuator 10 and the deck or other fixed structure is through contact with the abutments or brackets 16. These brackets prevent rotation of the actuator but do not otherwise position or restrain the actuator. With this arrangement, alignment of the shaft 12 and actuator 10 with respect to the fixed reference of the anchors or other conventional supporting surface is totally unnecessary.

Torque is applied to the rotary member 26 by four pistons simultaneously. With reference to FIG. 3, rotation of the rotary member 26 in a counterclockwise direction is accomplished by supplying fluid under pressure to the ports 46 of cylinders 22a, c and 22f, h. At the same time, the ports of the other cylinders are connected to exhaust. The four pistons 23 and the piston rods 24 act as a couple on the diametrically opposite slots 90, 92, through the coupling assemblies 28, to rotate the member 26 and shaft 12 counterclockwise. Rotation in the opposite direction is obtained by reversing the flow of fluid into the cylinders.

As the piston rods 24 reciprocate, each bearing block 100 rotates relative to the connecting pin 96 because of the change in annular relationship of the slots 90, 92 relative to the path of reciprocation of the piston rods. At the same time, the distance between the central axis of the vertical shaft 12 and the pins 96 changes. As this occurs, the bearing blocks 100 slide radially of the rotary member 26 along the slots 90, 92. The length of the diametrically opposite slots 90, 92 facilitates such sliding so that the connection between the piston rods and the rotary member is maintained throughout the complete stroke of each piston. This slot length should be sufficient to facilitate a significant degree of rotation of the shaft. Typically, it is possible to rotate the shaft 12 approximately onefifth of a revolution in either direction with a convenient slot length.

As the pistons are reciprocated and the rotary member 26 is rotated to rotate the rudder stock, a reaction force tends to rotate the actuator 10 in the opposite direction. The abutments or brackets 16 absorb such reaction torque and maintain the actuator 10 in constant position. As a result, the movement of the pistons and rods is directly transferred to the shaft 12 to rotate the shaft and the associated rudder. Because the abutments 16 are not connected to the actuator, they have no effect on the alignment of the cylinders 22 and piston rods 24.

As described above, a steering mechanism for a ship or the like has been provided that couples directly to and is supported by the upper end of a rudder stock. The structure is compact, capable of exerting high torque without excessive wear, performs accurately and reliably and eliminates the problems of alignment between the shaft and a fixed support. The construction facilitates repair and replacement of parts without complete disassembly, and permits one half of the actuator to be removed while the other half remains functioning.

Another steering mechanism for a ship, embodying the present invention, is shown in FIGS. 6 to 11 of the drawings. The mechanism includes a fluid actuator 200 constructed to be mounted directly to the hull of the ship adjacent the upper end of a rudder stock, indicated at 202. The basic components of the actuator 200 include cylinder support structure, including two housings 206 and 208 spaced apart laterally to receive the rudder stock 202 therebetween, each housing comprised of two spaced portions 206a, 206b, and 208a, b respectively, a plurality of opposed cylinders 210 extending from the housings four rains 212 each reciprocable within opposed pairs of cylinders 210 and extending between spaced portions of the housings, a rotary member in the form ofa tiller 214 attached to the rudder stock 202, and two coupling assemblies 216a, 216b, interconnecting the rams 212 and the tiller 214.

1n the preferred embodiment shown, the actuator utilizes eight separate cylinders 210a, b, c, d, e,f, g, h. Cylinders 2102,

5 fare not shown in FIGS. 6 and 7, but are directly beneath cylinders 210g, h and are laterally opposite cylinders 210a, b. The cylinders are arranged in opposed, aligned pairs 210a, b; 210c, a; 210e,f; e, f; and 210g, h.

As best shown in connection with cylinder 210C in FIG. 6, open inner ends of each cylinder are connected to the respective housing portions 206,b and 208a, b and the cylinders extend outwardly from the housings. Each housing portion 206a,b and 208a, b has a vertical support portion 206av, 206bv, 208av, 208bv welded to a bottom hold down plate 2060b, 206kb, 208ab, 208bb, The hold down plates each include a plurality of holes 206ah, 206bh, 208ah, 208bh to accommodate bolting the hold down plates to the hull ofa ship. Each of the vertical support portions have vertically aligned horizontally extending cylindrical openings to receive the inner ends of the cylinders 210. One such opening associated with the vertical support 206av is indicated at 218 in FIG. 6.

Each cylinder 210 is constructed in the same manner, and only the detailed construction of cylinder 210: 'will be described. As best shown in FIG. 6, the cylinder 210: is formed ofa tubular wall 220, which may be formed of steel or other suitable material. An open inner end 221, also shown in part in FlG. 11, has a reduced outside diameter and an enlarged inside diameter, and is received in the circular opening 218 in the vertical support portion 206av of the housing 2060. A radial face 222 formed in the wall 220 by the reduced outside diameter at the end portion 221 abuts against the outside surface of the vertical support portion 2060. This locates the tubular wall 220 with respect to the support structure. As best shown in FIG. 11, the portion 221 of enlarged inside and reduced outside diameter accommodates an annular cylinder bushing 224 that provides one of two spaced supports for the reciprocable ram 212 associated with the cylinder. The cylinder bushing 224 carries an annular wiper 225 and the bushing is spaced from the end of the cylinder wall by a packing 226 and a gland bushing 227. An outside wiper 228 is secured against the gland bushing 227 and the bushing assembly is retained by a flange 230 secured to the vertical support 206av by threaded studs 231 and nuts 232. Shims 233 between the flange 230 and the vertical support structure 206av permit adjustment of the location of the flange 230.

With similar cylinder bushings located at the inner ends of all cylinders, the rams 212 are each supported at spaced locations that reduce to a minimum the length of the span of each ram between support points, thereby minimizing distortion or deflection of the ram by components of force tending to bow the rams during operation.

The outer ends of the eight cylinders are closed by four end caps 236a-d of identical construction. As shown, the outer end of the tube 220 is closed by an end cap 2360, which is made of aluminum or other suitable material, and which is provided with a port 238 through which fluid under pressure can be introduced to the cylinder 2100 to drive the ram 212, or through which fluid can be exhausted to permit movement of the ram 212 toward the end cap. The end cap 236a fits over the outer end of the tubular wall 220. The outer end of the tubular wall 210 is of reduced diameter to receive and locate the end cap 236. The reduced diameter portion includes an O-ring 239 in an annular groove'to provide a seal between a cylindrical recess 240 in the end cap 236a that receives the outer end of the tubular wall 220. Each end cap 236 is rectangular in shape and extends across two vertically adjacent cylinders, as best shown in connection with the end cap 236C in FIG. 8. The port 238 is connected through internal conduits with the ends of both cylinders closed by the end cap and communicates I with a main conduit and fluid source and reservoir (not Shown) in the same manner as explained in more detail in connection with the first described embodiment.

Tie rods 246 extend the length of each cylinder 210. One end of each tie rod 246 is threaded as shown at 247 in connection with the cylinder 210g, and is received in a threaded bore 248 in an outwardly facing surface of the respective housing portion 2060, 206b, 2081:, 208b. The opposite end of each tie rod extends through one of a plurality of holes in the associated end cap 236. This opposite end is threaded and a nut 249 is threaded on the end ofthe tie rod 246 to clamp the end cap against the ends of the two associated cylinders.

The rams 212 are solid elongated cylindrical members having opposite flat ends 242, 243 (FIG. 6) which are selectively acted upon and reciprocated by fluid introduced to the cylinders through the ports 238. The rams 212 are of sufficient length to at all times extend between the associated pair of two opposed cylinders. spanning the distance between the pairs of housings on each side ofthe rudder stock.

Two transversely spaced, longitudinally extending tubes 252, 253 and two lower tubes 254, 255 are connected to and extend between the two spaced housing portions 206a, 20Gb of housing 206 to maintain the two spaced portions in fixed relationship and to increase the rigidity of the cylinder supports. At the same time, central portions of the rams 212 associated with the housing portions 206a, 206b remain exposed for inspection and access to the coupling assembly 216a. This facilitates maintenance and repair. Similarly, a pair of upper tubes 256, 257 and lower tubes (not shown) extend between the housing portions 208a, 2081) of housing 208.

With reference to F105. 6 and 8, the tiller 214 has a central cylindrical hub 2140 with a central cylindrical bore 265 that fits about the upper end of the rudder stock 202. Keys 266 in keyways of the central bore 265 and rudder stock 202 prevent relative rotation between the tiller and rudder stock. A hold down plate 267 shown in dotted line in FIG. 7 but omitted from FIG. 6 for illustrative purposes, is secured to the top of the rudder stock and retains the tiller.

The tiller 214 has a platelike portion 214b that extends from the hub portion 214a, is elongated into opposite directions and extends between the vertically spaced rams 212 on each side of the rudder stock 202. See FIG. 7. Two slots 272, 273 are formed in opposite elongated ends of the platelike portion 214b, extending radially of the rudder stock 202 in diametrically opposite directions. The radial slot 272 receives the coupling assembly 216a, and the radial slot 273 receives the coupling assembly 216b, which are carried by the rams 212 on each side of the rudder stock 202. The inner side surfaces of each radial slot 272, 273 are formed with a radius that provides concave cylindrical surfaces indicated at 272a, 272b in connection with the slot 272, with the center of curvature located along the radial centerline of the slot. Self-aligning bearings indicated at 274, 275 in connection with the slot 272 and having back surfaces 274a, 275a ,radiused to be received by the cylindrical surfaces of the slot and with flat parallel facing front surfaces 274b, 2751) are mounted against the radiused surfaces of the slot for limiting floating movement about the radial centerline of the slot. These bearings automatically align with facing surfaces of the coupling assemblies 216a, b, notwithstanding any misalignment of other actuator parts which may result in the axis of the coupling assembly being other than precisely parallel to the axis of the rudder stock. The manner in which such self-aligning bearings can be mounted for floating movement is well known in the art and, for example, can be accomplished by securing the bearings with cap screws in oversized bearing holes.

Each coupling assembly 2160, 216b extends between upper and lower spaced rams 212 on each side of the shaft 202. The upper and lower rams each include a vertical through bore 276, as best shown in FIG. 9, at the center of each ram. A single connecting pin 278 extends through the bores 276 of each pair of rams. The pin 278 has a groove or keyway 280 extending diametrically across a flat top surface 281 of the pin. A key 284 fits within the groove 280 and extends beyond the pin 278 in the longitudinal direction of the associated ram 212. The extending portions of the key 284 are received in grooves in the ram 212 on opposite sides of the vertical through bore 276. The key 284 is secured to the pin 278 by a bolt 285. Thus, the key 284 retains the pin 278in proper vertical position and prevents rotation of the pin during reciprocation of the rams 212. This eliminates wear between the pin and the rams.

A tiller block 290 surrounds a central portion of each connecting pin 278, between upper and lower spaced rams 214. As best illustrated in FIGS. 6, 9 and 10, the tiller blocks 290 are essentially square in plan and cross section, and fit within a respective radial slot 272, 273 of the tiller 214. The pin 278 associated with each pair of rams 212 is located in a central through bore 291 of the associated tiller block. The central bore includes lubricating passageways 292 that communicate with a grease fitting 293. The central passageway 297 is counterbored at opposite ends to receive pin bearings 296, 297

which facilitate relative rotation between the pin 278 and the tiller block 290 when the rams 212 are reciprocated. Outer ends of the pin bearings 296, 297 bear against flat seats 298, 299, respectively in the facing surfaces of the rams to hold the tiller block in proper vertical location within the slot of the tiller.

Two flat bearing plates 300, 301 are recessed in two opposite faces 302, 303, respectively of the tiller block, and abut in sliding relationship the opposite flat faces 274b, 27517 of the self-aligning bearings 274, 275 carried by the tiller 214. The flat bearing plates 300, 301 are formed of sintered bronze. impregnated with lubricant, such as oil, and not only facilitate relative sliding of the tiller block along the respective slot 272, 273 of the tiller, i.e., radially of the rudder stock, during reciprocation of the rams, but also permit relative tilting of the pin 278 and tiller block 290 about an axis across the slot. This latter movement, in combination with the adjustment permitted by the self-aligning bearings 274, 275, accommodates universal movement of the pin 278 and tiller block 290 relative to the tiller 214. At the same time, a relatively large flat surface or interface is provided between the tiller and the tiller block to withstand the high forces required in use. The large surface area and effective lubrication under pressure provided by the sintered bronze bearing plates 300, 301 reduces galling or scoring of the bearing surfaces that otherwise might occur due to the large forces involved. The double rams and coupling assembly construction facilitate the use of a single tiller between the vertically spaced rams, rather than a double or yoked tiller that would be required to straddle a single ram. This simplifies construction of the tiller, assures balanced forces on the coupling assembly and provides a reliable device that can continue to function in the event of damage to or failure of a cylinder.

With the embodiment as described in connection with FIGS. 6 to 11, the cylinders 210 are supported in fixed relationship to the hull of the ship. Nevertheless, because of the construction of the coupling assemblies 216 that interconnect the rams 212 with the tiller 214, critical alignment of the housings housing portions 206a, b, 2080, b and the opposed cylinders 210 is not required. Distortion of the rams 212 is minimized by virtue of their rugged construction and the relatively short distance between points of sliding support at the inwardly facing ends of the opposed cylinders. The housing construction is simple and rugged and provides access to the rams and coupling assemblies. In use, the cylinders on diametrically opposite sides of the rudder stock actuated as couples to rotate the tiller 214, as explained in connection with the first-described embodiment. By virtue of the separate housings, the cylinders and housings on one side of the rudder stock can be removed, repaired or replaced while the actuator components on the opposite side of the rudder stock remain operative. This is particularly important in connection with military ships, in which hull distortion or damage is more likely than in other ships and in which continued operation is extremely important. In this connection, the construction of the coupling assemblies and the universal movement provided between the connecting pin, tiller, and rams, will accommodate hull distortion and accompanying changes in cylinder alignment to a substantial extent without binding the movable parts.

In operation, the rams 212 reciprocate in response to the supply and exhaust of fluid under pressure to and from the ports 238 of the cylinders. Each tiller block 290 rotates relative to the connecting pin 278 during reciprocation of the rams because of the change in angular relationship ofthe radial slots 272, 273, relative to the path of reciprocation of the rams. At the same time, the distance between the central axis of the rudder stock 202 and the pins 278 changes. As this occurs, the tiller blocks 290 slide radially of the rudder stock 202 along the slots 272, 273, bearing against the self-aligning bearings 274, 275. The length of the diametrically opposite slots 272, 273 facilitates such sliding so that the connection between the rams and the tiller is maintained throughout the complete stroke of each ram. The reaction force generated when the rams are reciprocated and the tiller rotated, is resisted in this embodiment by the housings 206208, which are directly secured to the hull of the ship. As a result, the movement of the rams is directly transferred to the tiller 214 and rudder stock 202.

A modified construction and arrangement of actuators embodying the present invention is shown in FIG. 12, in which two actuators 310, 312, each having two vertically aligned pairs of horizontally opposed cylinders corresponding substantially to one-half of the actuator 200, are used to rotate two rudder stocks 314, 316 on a ship having two rudders. One pair of opposed cylinders 311a, b of actuator 310 and one pair of opposed cylinders 313a, b of actuator 312 are shown in the drawings. The actuators 310, 312 each have a single support housing 318, 319, respectively, connected directly to the hull of the ship. Except for the single housing rather than spaced housings with connecting tubes as in the embodiment of FIG. 6, the actuators 310, 312 are constructed identically to each half of the actuator 200.

A tiller 322 is keyed to the upper end of the rudder stock 314, and a tiller 323 is keyed to the upper end of the rudder stock 316. Each of these tillers has a single radial slot 325, 326, respectively that receives a coupling assembly 327, 328 of the respective actuator carried by reciprocable rams, upper rams 329, 330 being shown. Each coupling assembly is constructed in the manner already described in connection with the actuator of FIG. 6. Elongated openings 331, 332 above provide access to the coupling assemblies. A connecting link 333 is pivotally attached to each tiller 322, 323 diametrically opposite from the radial slot 325, 326, as by pivot pins 334, 335. The connecting link 333 assures coordinated movement of the tillers 322, 323 when the actuators 310, 312 are energized to rotate the tillers.

An actuator 200 is shown in FIG. 13 of the drawings, similar in all respects to the actuator 200 of FIG. 6, except for a modified cylinder construction, indicated at 210', and associated modifications in the support housings. The cylinder 210' is in the form of an integral casting having a closed outer end 335 and a circular mounting flange 336 surrounding the open inwardly facing end through which the associated ram 212' extends. The mounting flange 236 is secured directly to a housing 20612 and preferably is recessed into a counterbore in the housing about the central aperture that receives the ram 212. The mounting flange is secured to the housing by suitable clamping bolts 338. The inner surface of the cylinder 210 is machined to a cylindrical contour and a port (not shown) through which fluid is supplied or exhausted from the cylinder is formed in the outer end 335 to connect the inside of the cylinder with a source of fluid pressure or a fluid reservoir. A suitable bushing (not shown) for slidably supporting the ram 212 is mounted within the housing 206b, along with a suitable packing gland and wiper. This construction provides a compact design of low weight and high strength, which by virtue of its unitary cylinder construction is completely sealed at the outer ends, and provides high efficiency and reliability.

Each embodiment described provides a compact and reliable actuator that eliminates the need for critical alignment relative to the rudder stock of the ship. The construction assures even load distribution on components throughout the actuator, provides lubrication of the coupling assembly where high sliding friction is developed, and distributes the high load pressures over a relatively large area of the coupling assembly to avoid damage to bearing components. Each actuator half is a complete unit that can be shop-tested and that can be quickly and conveniently installed on a ship, with two such units forming an efflcient couple to actuate the tiller connected to the rudder stock. The actuator is either installed on the foundations of the ship hull or suspended from the rudder stock without costly shimming or time consuming alignment. In the embodiment installed on the rudder stock, actuator alignment is independent of adjacent structure. In the embodiment mounted directly to the hull, self-alignment of the coupling mechanism with the tiller is automatic by virtue of the universal movement permitted. ln each embodiment onehalf of the actuator can be removed while the remaining half can continue to function.

While in the foregoing disclosure a preferred embodiment of the invention has been described in detail, it will readily be apparent that many changes and variations may be made therein without departing from the spirit and scope of the invention, as set forth in the appended claims.

What I claim is:

l. A steering mechanism for a rudder of a ship comprising: cylinder support structure on two opposite sides of a rudder stock, first and second pairs of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said second pair of opposed cylinders being located above and vertically aligned with the first pair, a first elongated reciprocable member received at opposite ends within said first pair of opposed cylinders and extending alongside the rudder stock, a second elongated reciprocablemember received at opposite ends within said second pair of opposed cylinders and extending alongside the rudder stock parallel to the first reciprocable member, a tiller fixed to the rudder stock and having a slot extending radially thereof, the portion of the tiller that includes the slot being located between the first and second reciprocable members, opposite side surfaces of the slot and the tiller including self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock, means connected to and located between said reciprocable members, engaged with the tiller and slidable within the slot thereof during reciprocation of said reciprocable members and universally movable relative to the slot, said means including a selflubricating bearing surface that slides relative to the self-aligning bearings in the tiller slot, and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members.

2. The steering mechanism of claim 1 including means to prevent rotation of the cylinder support structure relative to the rudder stock.

3. The steering mechanism of claim I wherein the means connected between the reciprocable members further includes a cylindrical connecting pin extending through apertures in the reciprocable members, a key preventing relative rotation between the pin and reciprocable members, a tiller block about a portion of the pin between the reciprocable member and wherein a self-lubricating bearing surface is carried by the tiller block on two opposite sides in engagement with the self-aligning bearings in the tiller slot.

4. The steering mechanism of claim 1 wherein the cylinders are one-piece casting with an integral end wall and a mounting flange at theopen end.

5. The steering mechanism of claim 1 including bearing means adjacent the open end of each opposed cylinder for supporting the reciprocable member received in said cylinders.

6. The steering mechanism of claim 5 wherein the reciprocable member is a ram with the entire portions receivable within the opposed cylinders being smooth-walled and cylindrical.

7. A steering mechanism for a rudder of a ship comprising: cylinder support structure on two opposite sides of a rudder stock, first and second pairs of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said second pair of opposed cylinders being located above and vertically aligned with the first pair. a first elongated reciprocable member received at opposite ends within said first pair of opposed cylinders and extending alongside the rudder stock, a second elongated reciprocable member received at opposite ends within said second pair ofopposed cylinders and extending alongside the rudder stock parallel to the first reciprocable member, a tiller fixed to the rudder stock and having a slot extending radially thereof, the portionof the tiller that includes the slot being located between the first and second reciprocable members, opposite side surfaces of the slot and the tiller including self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock, means connected to and located between said reciprocable members, engaged with the tiller and slidable within the slot thereofduring reciprocation of said reciprocable members, and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members.

8. A steering mechanism for a rudder ofa ship comprising: cylinder support structure beside a rudder stock; a pair of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure; an elongated reciprocable member received at opposite ends within said opposed cylinders and with a portion extending between the cylinders passing alongside the rudder stock; a tiller fixed to the rudder stock and having a slot extending radially thereof; opposite side surfaces of the slot in the tiller include self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock and having flat bearing surfaces facing inwardly of the slot; means, including a self-lubricating bearing surface, connected to the reciprocable member and engaged with said bearing surfaces in the slot of the tiller, slidable within the slot during reciprocation of said reciprocable member and universally movable relative to the tiller; and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable member.

9. The steering mechanism of claim 8 wherein said means slidable in the slot of the tiller includes a cylindrical pin connected to and extending transversely of said reciprocable member and a block rotatably carried on said pin and carrying flat bearing plates engaged with said flat bearing surfaces of the self-aligning bearings in the side surfaces of the tiller slot.

10. A steering mechanism for a rudder ofa ship comprising: cylinder support structure adapted to be supported against rotation adjacent a rudder stock of a ship; a pair of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said open ends being received in and directly surrounded by the housing structure; an elongated reciprocable member received at opposite ends within said opposed cylinders and with a portion extending between the cylinders and adapted to pass alongside the rudder stock; an annular cylinder-bushing located within the end of each cylinder that is received in and surrounded by the housing for rigidly supporting the reciprocable member for sliding at two locations spaced to minimize the unsupported span of the member; a bushing retainer secured to the housing; a rotary member adapted to be fixed to the rudder stock for rotating the rudder stock; means carried by said reciprocable member for engaging and rotating said rotary member; and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable member.

1 A steering mechanism for a rudder ofa ship comprising: housing means adapted to be supported against rotation adjacent a rotatable rudder stock of a ship; four pairs of opposed cylinders supported by said housing means, extending parallel to each other and transversely of the rudder stock, two pairs on one side of the shaft spaced axially from each other relative to the shaft and two pairs on an opposite side of the shaft similarly spaced; four parallel reciprocable members, two being vertically spaced each above another, each of the four received at opposite ends within a said pair of opposed cylinders and adapted to extend alongside the rudder stock; a tiller securable in fixed relationship to the rudder stock of a ship and having two slots extending radially thereof, diametrically opposite each other relative to the rudder stock; means extending between vertically spaced reciprocable members engageable with an slidable within the slots of said tiller and coupling said four reciprocable members to said tiller; and inlet and exhaust ports to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,595,193 Dated July 27, 1971 Inventofls) William E. Heese It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 59, after "forces" insert from Column 2, line 68, delete "lead" substitute load Column 3, line 56, delete "stock" substitute stocks Column 4, line 69, delete "22b" substitute 22a, b

Column 6, line 39, after "92" insert are Column 8, line 56, "206a, 206b" should be 206a, b

Column 8 line 58 insert a comma before "four rams" Column 9, line 58, delete "Shown" substitute shown Column 10, line 22, delete "into" substitute in two Column 10, line 36, after"275b", insert a comma Column 14, claim 11, line 16, delete "an substitute and Signed and sealed this 26th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOT'l'SCI-IALK Attesting Officer- Commissionerof Pa ents 

1. A steering mechanism for a rudder of a ship comprising: cylinder support structure on two opposite sides of a rudder stock, first and second pairs of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said second pair of opposed cylinders being located above and vertically aligned with the first pair, a first elongated reciprocable member received at opposite ends within said first pair of opposed cylinders and extending alongside the rudder stock, a second elongated reciprocable member received at opposite ends within said second pair of opposed cylinders and extending alongside the rudder stock parallel to the first reciprocable member, a tiller fixed to the rudder stock and having a slot extending radially thereof, the portion of the tiller that includes the slot being located between the first and second reciprocable members, opposite side surfaces of the slot and the tiller including self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock, means connected to and located between said reciprocable members, engaged with the tiller and slidable within the slot thereof during reciprocation of said reciprocable members and universally movable relative to the slot, said means including a self-lubricating bearing surface that slides relative to the self-aligning bearings in the tiller slot, and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members.
 2. The steering mechanism of claim 1 including means to prevent rotation of the cylinder support structure relative to the rudder stock.
 3. The steering mechanism of claim 1 wherein the means connected between the reciprocable members further includes a cylindrical connecting pin extending through apertures in the reciprocable members, a key preventing relative rotation between the pin and reciprocable members, a tiller block about a portion of the pin between the reciprocable member and wherein a self-lubricating bearing surface is carried by the tilleR block on two opposite sides in engagement with the self-aligning bearings in the tiller slot.
 4. The steering mechanism of claim 1 wherein the cylinders are one-piece casting with an integral end wall and a mounting flange at the open end.
 5. The steering mechanism of claim 1 including bearing means adjacent the open end of each opposed cylinder for supporting the reciprocable member received in said cylinders.
 6. The steering mechanism of claim 5 wherein the reciprocable member is a ram with the entire portions receivable within the opposed cylinders being smooth-walled and cylindrical.
 7. A steering mechanism for a rudder of a ship comprising: cylinder support structure on two opposite sides of a rudder stock, first and second pairs of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said second pair of opposed cylinders being located above and vertically aligned with the first pair, a first elongated reciprocable member received at opposite ends within said first pair of opposed cylinders and extending alongside the rudder stock, a second elongated reciprocable member received at opposite ends within said second pair of opposed cylinders and extending alongside the rudder stock parallel to the first reciprocable member, a tiller fixed to the rudder stock and having a slot extending radially thereof, the portion of the tiller that includes the slot being located between the first and second reciprocable members, opposite side surfaces of the slot and the tiller including self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock, means connected to and located between said reciprocable members, engaged with the tiller and slidable within the slot thereof during reciprocation of said reciprocable members, and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members.
 8. A steering mechanism for a rudder of a ship comprising: cylinder support structure beside a rudder stock; a pair of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure; an elongated reciprocable member received at opposite ends within said opposed cylinders and with a portion extending between the cylinders passing alongside the rudder stock; a tiller fixed to the rudder stock and having a slot extending radially thereof; opposite side surfaces of the slot in the tiller include self-aligning bearings adjustable about the centerline of the slot that extends radially of the rudder stock and having flat bearing surfaces facing inwardly of the slot; means, including a self-lubricating bearing surface, connected to the reciprocable member and engaged with said bearing surfaces in the slot of the tiller, slidable within the slot during reciprocation of said reciprocable member and universally movable relative to the tiller; and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable member.
 9. The steering mechanism of claim 8 wherein said means slidable in the slot of the tiller includes a cylindrical pin connected to and extending transversely of said reciprocable member and a block rotatably carried on said pin and carrying flat bearing plates engaged with said flat bearing surfaces of the self-aligning bearings in the side surfaces of the tiller slot.
 10. A steering mechanism for a rudder of a ship comprising: cylinder support structure adapted to be supported against rotation adjacent a rudder stock of a ship; a pair of opposed cylinders supported by and extending from said support structure with opposed ends open and spaced apart by said housing structure, said open ends being received in and directly surrounded by the housing structure; an elongated reciprocable member received at opposite ends within said opposed cylinders and with a portion extending between the cylindErs and adapted to pass alongside the rudder stock; an annular cylinder-bushing located within the end of each cylinder that is received in and surrounded by the housing for rigidly supporting the reciprocable member for sliding at two locations spaced to minimize the unsupported span of the member; a bushing retainer secured to the housing; a rotary member adapted to be fixed to the rudder stock for rotating the rudder stock; means carried by said reciprocable member for engaging and rotating said rotary member; and means to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable member.
 11. A steering mechanism for a rudder of a ship comprising: housing means adapted to be supported against rotation adjacent a rotatable rudder stock of a ship; four pairs of opposed cylinders supported by said housing means, extending parallel to each other and transversely of the rudder stock, two pairs on one side of the shaft spaced axially from each other relative to the shaft and two pairs on an opposite side of the shaft similarly spaced; four parallel reciprocable members, two being vertically spaced each above another, each of the four received at opposite ends within a said pair of opposed cylinders and adapted to extend alongside the rudder stock; a tiller securable in fixed relationship to the rudder stock of a ship and having two slots extending radially thereof, diametrically opposite each other relative to the rudder stock; means extending between vertically spaced reciprocable members engageable with an slidable within the slots of said tiller and coupling said four reciprocable members to said tiller; and inlet and exhaust ports to introduce fluid to and exhaust fluid from said cylinders to reciprocate said reciprocable members. 